1 /* 2 * USB Skeleton driver - 2.2 3 * 4 * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com) 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License as 8 * published by the Free Software Foundation, version 2. 9 * 10 * This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c 11 * but has been rewritten to be easier to read and use. 12 * 13 */ 14 15 #include <linux/kernel.h> 16 #include <linux/errno.h> 17 #include <linux/slab.h> 18 #include <linux/module.h> 19 #include <linux/kref.h> 20 #include <linux/uaccess.h> 21 #include <linux/usb.h> 22 #include <linux/mutex.h> 23 24 25 /* Define these values to match your devices */ 26 #define USB_SKEL_VENDOR_ID 0xfff0 27 #define USB_SKEL_PRODUCT_ID 0xfff0 28 29 /* table of devices that work with this driver */ 30 static const struct usb_device_id skel_table[] = { 31 { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) }, 32 { } /* Terminating entry */ 33 }; 34 MODULE_DEVICE_TABLE(usb, skel_table); 35 36 37 /* Get a minor range for your devices from the usb maintainer */ 38 #define USB_SKEL_MINOR_BASE 192 39 40 /* our private defines. if this grows any larger, use your own .h file */ 41 #define MAX_TRANSFER (PAGE_SIZE - 512) 42 /* MAX_TRANSFER is chosen so that the VM is not stressed by 43 allocations > PAGE_SIZE and the number of packets in a page 44 is an integer 512 is the largest possible packet on EHCI */ 45 #define WRITES_IN_FLIGHT 8 46 /* arbitrarily chosen */ 47 48 /* Structure to hold all of our device specific stuff */ 49 struct usb_skel { 50 struct usb_device *udev; /* the usb device for this device */ 51 struct usb_interface *interface; /* the interface for this device */ 52 struct semaphore limit_sem; /* limiting the number of writes in progress */ 53 struct usb_anchor submitted; /* in case we need to retract our submissions */ 54 struct urb *bulk_in_urb; /* the urb to read data with */ 55 unsigned char *bulk_in_buffer; /* the buffer to receive data */ 56 size_t bulk_in_size; /* the size of the receive buffer */ 57 size_t bulk_in_filled; /* number of bytes in the buffer */ 58 size_t bulk_in_copied; /* already copied to user space */ 59 __u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */ 60 __u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */ 61 int errors; /* the last request tanked */ 62 bool ongoing_read; /* a read is going on */ 63 spinlock_t err_lock; /* lock for errors */ 64 struct kref kref; 65 struct mutex io_mutex; /* synchronize I/O with disconnect */ 66 wait_queue_head_t bulk_in_wait; /* to wait for an ongoing read */ 67 }; 68 #define to_skel_dev(d) container_of(d, struct usb_skel, kref) 69 70 static struct usb_driver skel_driver; 71 static void skel_draw_down(struct usb_skel *dev); 72 73 static void skel_delete(struct kref *kref) 74 { 75 struct usb_skel *dev = to_skel_dev(kref); 76 77 usb_free_urb(dev->bulk_in_urb); 78 usb_put_dev(dev->udev); 79 kfree(dev->bulk_in_buffer); 80 kfree(dev); 81 } 82 83 static int skel_open(struct inode *inode, struct file *file) 84 { 85 struct usb_skel *dev; 86 struct usb_interface *interface; 87 int subminor; 88 int retval = 0; 89 90 subminor = iminor(inode); 91 92 interface = usb_find_interface(&skel_driver, subminor); 93 if (!interface) { 94 pr_err("%s - error, can't find device for minor %d\n", 95 __func__, subminor); 96 retval = -ENODEV; 97 goto exit; 98 } 99 100 dev = usb_get_intfdata(interface); 101 if (!dev) { 102 retval = -ENODEV; 103 goto exit; 104 } 105 106 retval = usb_autopm_get_interface(interface); 107 if (retval) 108 goto exit; 109 110 /* increment our usage count for the device */ 111 kref_get(&dev->kref); 112 113 /* save our object in the file's private structure */ 114 file->private_data = dev; 115 116 exit: 117 return retval; 118 } 119 120 static int skel_release(struct inode *inode, struct file *file) 121 { 122 struct usb_skel *dev; 123 124 dev = file->private_data; 125 if (dev == NULL) 126 return -ENODEV; 127 128 /* allow the device to be autosuspended */ 129 mutex_lock(&dev->io_mutex); 130 if (dev->interface) 131 usb_autopm_put_interface(dev->interface); 132 mutex_unlock(&dev->io_mutex); 133 134 /* decrement the count on our device */ 135 kref_put(&dev->kref, skel_delete); 136 return 0; 137 } 138 139 static int skel_flush(struct file *file, fl_owner_t id) 140 { 141 struct usb_skel *dev; 142 int res; 143 144 dev = file->private_data; 145 if (dev == NULL) 146 return -ENODEV; 147 148 /* wait for io to stop */ 149 mutex_lock(&dev->io_mutex); 150 skel_draw_down(dev); 151 152 /* read out errors, leave subsequent opens a clean slate */ 153 spin_lock_irq(&dev->err_lock); 154 res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0; 155 dev->errors = 0; 156 spin_unlock_irq(&dev->err_lock); 157 158 mutex_unlock(&dev->io_mutex); 159 160 return res; 161 } 162 163 static void skel_read_bulk_callback(struct urb *urb) 164 { 165 struct usb_skel *dev; 166 167 dev = urb->context; 168 169 spin_lock(&dev->err_lock); 170 /* sync/async unlink faults aren't errors */ 171 if (urb->status) { 172 if (!(urb->status == -ENOENT || 173 urb->status == -ECONNRESET || 174 urb->status == -ESHUTDOWN)) 175 dev_err(&dev->interface->dev, 176 "%s - nonzero write bulk status received: %d\n", 177 __func__, urb->status); 178 179 dev->errors = urb->status; 180 } else { 181 dev->bulk_in_filled = urb->actual_length; 182 } 183 dev->ongoing_read = 0; 184 spin_unlock(&dev->err_lock); 185 186 wake_up_interruptible(&dev->bulk_in_wait); 187 } 188 189 static int skel_do_read_io(struct usb_skel *dev, size_t count) 190 { 191 int rv; 192 193 /* prepare a read */ 194 usb_fill_bulk_urb(dev->bulk_in_urb, 195 dev->udev, 196 usb_rcvbulkpipe(dev->udev, 197 dev->bulk_in_endpointAddr), 198 dev->bulk_in_buffer, 199 min(dev->bulk_in_size, count), 200 skel_read_bulk_callback, 201 dev); 202 /* tell everybody to leave the URB alone */ 203 spin_lock_irq(&dev->err_lock); 204 dev->ongoing_read = 1; 205 spin_unlock_irq(&dev->err_lock); 206 207 /* submit bulk in urb, which means no data to deliver */ 208 dev->bulk_in_filled = 0; 209 dev->bulk_in_copied = 0; 210 211 /* do it */ 212 rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL); 213 if (rv < 0) { 214 dev_err(&dev->interface->dev, 215 "%s - failed submitting read urb, error %d\n", 216 __func__, rv); 217 rv = (rv == -ENOMEM) ? rv : -EIO; 218 spin_lock_irq(&dev->err_lock); 219 dev->ongoing_read = 0; 220 spin_unlock_irq(&dev->err_lock); 221 } 222 223 return rv; 224 } 225 226 static ssize_t skel_read(struct file *file, char *buffer, size_t count, 227 loff_t *ppos) 228 { 229 struct usb_skel *dev; 230 int rv; 231 bool ongoing_io; 232 233 dev = file->private_data; 234 235 /* if we cannot read at all, return EOF */ 236 if (!dev->bulk_in_urb || !count) 237 return 0; 238 239 /* no concurrent readers */ 240 rv = mutex_lock_interruptible(&dev->io_mutex); 241 if (rv < 0) 242 return rv; 243 244 if (!dev->interface) { /* disconnect() was called */ 245 rv = -ENODEV; 246 goto exit; 247 } 248 249 /* if IO is under way, we must not touch things */ 250 retry: 251 spin_lock_irq(&dev->err_lock); 252 ongoing_io = dev->ongoing_read; 253 spin_unlock_irq(&dev->err_lock); 254 255 if (ongoing_io) { 256 /* nonblocking IO shall not wait */ 257 if (file->f_flags & O_NONBLOCK) { 258 rv = -EAGAIN; 259 goto exit; 260 } 261 /* 262 * IO may take forever 263 * hence wait in an interruptible state 264 */ 265 rv = wait_event_interruptible(dev->bulk_in_wait, (!dev->ongoing_read)); 266 if (rv < 0) 267 goto exit; 268 } 269 270 /* errors must be reported */ 271 rv = dev->errors; 272 if (rv < 0) { 273 /* any error is reported once */ 274 dev->errors = 0; 275 /* to preserve notifications about reset */ 276 rv = (rv == -EPIPE) ? rv : -EIO; 277 /* report it */ 278 goto exit; 279 } 280 281 /* 282 * if the buffer is filled we may satisfy the read 283 * else we need to start IO 284 */ 285 286 if (dev->bulk_in_filled) { 287 /* we had read data */ 288 size_t available = dev->bulk_in_filled - dev->bulk_in_copied; 289 size_t chunk = min(available, count); 290 291 if (!available) { 292 /* 293 * all data has been used 294 * actual IO needs to be done 295 */ 296 rv = skel_do_read_io(dev, count); 297 if (rv < 0) 298 goto exit; 299 else 300 goto retry; 301 } 302 /* 303 * data is available 304 * chunk tells us how much shall be copied 305 */ 306 307 if (copy_to_user(buffer, 308 dev->bulk_in_buffer + dev->bulk_in_copied, 309 chunk)) 310 rv = -EFAULT; 311 else 312 rv = chunk; 313 314 dev->bulk_in_copied += chunk; 315 316 /* 317 * if we are asked for more than we have, 318 * we start IO but don't wait 319 */ 320 if (available < count) 321 skel_do_read_io(dev, count - chunk); 322 } else { 323 /* no data in the buffer */ 324 rv = skel_do_read_io(dev, count); 325 if (rv < 0) 326 goto exit; 327 else 328 goto retry; 329 } 330 exit: 331 mutex_unlock(&dev->io_mutex); 332 return rv; 333 } 334 335 static void skel_write_bulk_callback(struct urb *urb) 336 { 337 struct usb_skel *dev; 338 339 dev = urb->context; 340 341 /* sync/async unlink faults aren't errors */ 342 if (urb->status) { 343 if (!(urb->status == -ENOENT || 344 urb->status == -ECONNRESET || 345 urb->status == -ESHUTDOWN)) 346 dev_err(&dev->interface->dev, 347 "%s - nonzero write bulk status received: %d\n", 348 __func__, urb->status); 349 350 spin_lock(&dev->err_lock); 351 dev->errors = urb->status; 352 spin_unlock(&dev->err_lock); 353 } 354 355 /* free up our allocated buffer */ 356 usb_free_coherent(urb->dev, urb->transfer_buffer_length, 357 urb->transfer_buffer, urb->transfer_dma); 358 up(&dev->limit_sem); 359 } 360 361 static ssize_t skel_write(struct file *file, const char *user_buffer, 362 size_t count, loff_t *ppos) 363 { 364 struct usb_skel *dev; 365 int retval = 0; 366 struct urb *urb = NULL; 367 char *buf = NULL; 368 size_t writesize = min(count, (size_t)MAX_TRANSFER); 369 370 dev = file->private_data; 371 372 /* verify that we actually have some data to write */ 373 if (count == 0) 374 goto exit; 375 376 /* 377 * limit the number of URBs in flight to stop a user from using up all 378 * RAM 379 */ 380 if (!(file->f_flags & O_NONBLOCK)) { 381 if (down_interruptible(&dev->limit_sem)) { 382 retval = -ERESTARTSYS; 383 goto exit; 384 } 385 } else { 386 if (down_trylock(&dev->limit_sem)) { 387 retval = -EAGAIN; 388 goto exit; 389 } 390 } 391 392 spin_lock_irq(&dev->err_lock); 393 retval = dev->errors; 394 if (retval < 0) { 395 /* any error is reported once */ 396 dev->errors = 0; 397 /* to preserve notifications about reset */ 398 retval = (retval == -EPIPE) ? retval : -EIO; 399 } 400 spin_unlock_irq(&dev->err_lock); 401 if (retval < 0) 402 goto error; 403 404 /* create a urb, and a buffer for it, and copy the data to the urb */ 405 urb = usb_alloc_urb(0, GFP_KERNEL); 406 if (!urb) { 407 retval = -ENOMEM; 408 goto error; 409 } 410 411 buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL, 412 &urb->transfer_dma); 413 if (!buf) { 414 retval = -ENOMEM; 415 goto error; 416 } 417 418 if (copy_from_user(buf, user_buffer, writesize)) { 419 retval = -EFAULT; 420 goto error; 421 } 422 423 /* this lock makes sure we don't submit URBs to gone devices */ 424 mutex_lock(&dev->io_mutex); 425 if (!dev->interface) { /* disconnect() was called */ 426 mutex_unlock(&dev->io_mutex); 427 retval = -ENODEV; 428 goto error; 429 } 430 431 /* initialize the urb properly */ 432 usb_fill_bulk_urb(urb, dev->udev, 433 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr), 434 buf, writesize, skel_write_bulk_callback, dev); 435 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; 436 usb_anchor_urb(urb, &dev->submitted); 437 438 /* send the data out the bulk port */ 439 retval = usb_submit_urb(urb, GFP_KERNEL); 440 mutex_unlock(&dev->io_mutex); 441 if (retval) { 442 dev_err(&dev->interface->dev, 443 "%s - failed submitting write urb, error %d\n", 444 __func__, retval); 445 goto error_unanchor; 446 } 447 448 /* 449 * release our reference to this urb, the USB core will eventually free 450 * it entirely 451 */ 452 usb_free_urb(urb); 453 454 455 return writesize; 456 457 error_unanchor: 458 usb_unanchor_urb(urb); 459 error: 460 if (urb) { 461 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma); 462 usb_free_urb(urb); 463 } 464 up(&dev->limit_sem); 465 466 exit: 467 return retval; 468 } 469 470 static const struct file_operations skel_fops = { 471 .owner = THIS_MODULE, 472 .read = skel_read, 473 .write = skel_write, 474 .open = skel_open, 475 .release = skel_release, 476 .flush = skel_flush, 477 .llseek = noop_llseek, 478 }; 479 480 /* 481 * usb class driver info in order to get a minor number from the usb core, 482 * and to have the device registered with the driver core 483 */ 484 static struct usb_class_driver skel_class = { 485 .name = "skel%d", 486 .fops = &skel_fops, 487 .minor_base = USB_SKEL_MINOR_BASE, 488 }; 489 490 static int skel_probe(struct usb_interface *interface, 491 const struct usb_device_id *id) 492 { 493 struct usb_skel *dev; 494 struct usb_endpoint_descriptor *bulk_in, *bulk_out; 495 int retval; 496 497 /* allocate memory for our device state and initialize it */ 498 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 499 if (!dev) 500 return -ENOMEM; 501 502 kref_init(&dev->kref); 503 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT); 504 mutex_init(&dev->io_mutex); 505 spin_lock_init(&dev->err_lock); 506 init_usb_anchor(&dev->submitted); 507 init_waitqueue_head(&dev->bulk_in_wait); 508 509 dev->udev = usb_get_dev(interface_to_usbdev(interface)); 510 dev->interface = interface; 511 512 /* set up the endpoint information */ 513 /* use only the first bulk-in and bulk-out endpoints */ 514 retval = usb_find_common_endpoints(interface->cur_altsetting, 515 &bulk_in, &bulk_out, NULL, NULL); 516 if (retval) { 517 dev_err(&interface->dev, 518 "Could not find both bulk-in and bulk-out endpoints\n"); 519 goto error; 520 } 521 522 dev->bulk_in_size = usb_endpoint_maxp(bulk_in); 523 dev->bulk_in_endpointAddr = bulk_in->bEndpointAddress; 524 dev->bulk_in_buffer = kmalloc(dev->bulk_in_size, GFP_KERNEL); 525 if (!dev->bulk_in_buffer) { 526 retval = -ENOMEM; 527 goto error; 528 } 529 dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL); 530 if (!dev->bulk_in_urb) { 531 retval = -ENOMEM; 532 goto error; 533 } 534 535 dev->bulk_out_endpointAddr = bulk_out->bEndpointAddress; 536 537 /* save our data pointer in this interface device */ 538 usb_set_intfdata(interface, dev); 539 540 /* we can register the device now, as it is ready */ 541 retval = usb_register_dev(interface, &skel_class); 542 if (retval) { 543 /* something prevented us from registering this driver */ 544 dev_err(&interface->dev, 545 "Not able to get a minor for this device.\n"); 546 usb_set_intfdata(interface, NULL); 547 goto error; 548 } 549 550 /* let the user know what node this device is now attached to */ 551 dev_info(&interface->dev, 552 "USB Skeleton device now attached to USBSkel-%d", 553 interface->minor); 554 return 0; 555 556 error: 557 /* this frees allocated memory */ 558 kref_put(&dev->kref, skel_delete); 559 560 return retval; 561 } 562 563 static void skel_disconnect(struct usb_interface *interface) 564 { 565 struct usb_skel *dev; 566 int minor = interface->minor; 567 568 dev = usb_get_intfdata(interface); 569 usb_set_intfdata(interface, NULL); 570 571 /* give back our minor */ 572 usb_deregister_dev(interface, &skel_class); 573 574 /* prevent more I/O from starting */ 575 mutex_lock(&dev->io_mutex); 576 dev->interface = NULL; 577 mutex_unlock(&dev->io_mutex); 578 579 usb_kill_anchored_urbs(&dev->submitted); 580 581 /* decrement our usage count */ 582 kref_put(&dev->kref, skel_delete); 583 584 dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor); 585 } 586 587 static void skel_draw_down(struct usb_skel *dev) 588 { 589 int time; 590 591 time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000); 592 if (!time) 593 usb_kill_anchored_urbs(&dev->submitted); 594 usb_kill_urb(dev->bulk_in_urb); 595 } 596 597 static int skel_suspend(struct usb_interface *intf, pm_message_t message) 598 { 599 struct usb_skel *dev = usb_get_intfdata(intf); 600 601 if (!dev) 602 return 0; 603 skel_draw_down(dev); 604 return 0; 605 } 606 607 static int skel_resume(struct usb_interface *intf) 608 { 609 return 0; 610 } 611 612 static int skel_pre_reset(struct usb_interface *intf) 613 { 614 struct usb_skel *dev = usb_get_intfdata(intf); 615 616 mutex_lock(&dev->io_mutex); 617 skel_draw_down(dev); 618 619 return 0; 620 } 621 622 static int skel_post_reset(struct usb_interface *intf) 623 { 624 struct usb_skel *dev = usb_get_intfdata(intf); 625 626 /* we are sure no URBs are active - no locking needed */ 627 dev->errors = -EPIPE; 628 mutex_unlock(&dev->io_mutex); 629 630 return 0; 631 } 632 633 static struct usb_driver skel_driver = { 634 .name = "skeleton", 635 .probe = skel_probe, 636 .disconnect = skel_disconnect, 637 .suspend = skel_suspend, 638 .resume = skel_resume, 639 .pre_reset = skel_pre_reset, 640 .post_reset = skel_post_reset, 641 .id_table = skel_table, 642 .supports_autosuspend = 1, 643 }; 644 645 module_usb_driver(skel_driver); 646 647 MODULE_LICENSE("GPL"); 648